Invention of biobased polymer alloys and their application in plastic automobile parts

Polyamide 11 (PA11), a 100% biobased plastic derived from inedible plants, and polypropylene (PP) were mixed with a reactive compatibilizer using a twin-screw extruder. The mechanical properties and morphology of the resulting injection-molded PP/PA11 bioalloys were investigated by flexural tests, Charpy notched impact tests, field-emission scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM), among other tests. We found that it was possible to control the morphology of the bioalloy and that it had a wide range of mechanical properties depending on the morphology. When the morphology of the bioalloy was a “ nanosalami” structure, as revealed by FE-SEM, the material had a Charpy notched impact strength of 70–85 kJ/m2, which is superior to that of polycarbonates, without a large reduction in the flexural modulus. TEM observations showed that the reactive compatibilizers were located in the interphase between the matrix and dispersed phase. The compatibilizers played a key role in improving impact strength. The bioalloy could be used for foam injection molding; therefore, it was able to be applied as a foamed door trim, resulting in an approximately 30% weight reduction for the plastic part.